In well-known communication systems, system controllers control both internal communications and external communications to system terminals. In certain systems, the system controller may also control adjunct apparatuses (voice mail systems, automatic call distributors, etc.) which provide new features and which may often require substantial communication interactions with the system controllers and terminals. Undesirably, providing these additional adjunct features may add significantly to the processing load which must be handled by the system controller. In some circumstances, this additional processing load may adversely affect the normal communication services provided by the system. What is desired is a communication system arrangement in which adjunct features may be provided without substantially adding to the processing load of the system controller.